fix(iOS, Tabs): defer scroll view behavior override until props are set

In Fabric, the mutation order for newly created views is Create → Insert → Update,
meaning mountChildComponentView fires before updateProps. This caused
overrideScrollViewContentInsetAdjustmentBehavior to use its default value (YES)
instead of the JS-provided value.

Defer the override call when props haven't been set yet and apply it in updateProps
once the prop value is known.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Ubax

ios/bottom-tabs/screen/RNSBottomTabsScreenComponentView.mm

@@ -32,6 +32,9 @@ @implementation RNSBottomTabsScreenComponentView {
 
   // We need this information to warn users about dynamic changes to behavior being currently unsupported.
   BOOL _isOverrideScrollViewContentInsetAdjustmentBehaviorSet;
+  // Tracks that the first child was mounted before props were set.
+  // The pending override will be applied once updateProps runs.
+  BOOL _needsScrollViewBehaviorOverride;
 #if !RCT_NEW_ARCH_ENABLED
   BOOL _tabItemNeedsAppearanceUpdate;
   BOOL _tabScreenOrientationNeedsUpdate;
@@ -372,6 +375,12 @@ - (void)updateProps:(const facebook::react::Props::Shared &)props
   // enabling us to warn users that dynamic changes are not supported.
   _isOverrideScrollViewContentInsetAdjustmentBehaviorSet = YES;
 
+  // Apply deferred scroll view override if a child was mounted before props arrived
+  if (_needsScrollViewBehaviorOverride) {
+    [self overrideScrollViewBehaviorInFirstDescendantChainIfNeeded];
+    _needsScrollViewBehaviorOverride = NO;
+  }
+
   if (newComponentProps.systemItem != oldComponentProps.systemItem) {
     _systemItem = rnscreens::conversion::RNSBottomTabsScreenSystemItemFromReactRNSBottomTabsScreenSystemItem(
         newComponentProps.systemItem);
@@ -465,7 +474,13 @@ - (void)mountChildComponentView:(UIView<RCTComponentViewProtocol> *)childCompone
   // overrideScrollViewBehavior and updateContentScrollViewEdgeEffects use first descendant chain
   // from screen to find ScrollView, that's why we're only interested in child mounted at index 0.
   if (index == 0) {
-    [self overrideScrollViewBehaviorInFirstDescendantChainIfNeeded];
+    // If the props were not set before the first child was mounted,
+    // we defer the override behavior application until props are set.
+    if (_isOverrideScrollViewContentInsetAdjustmentBehaviorSet) {
+      [self overrideScrollViewBehaviorInFirstDescendantChainIfNeeded];
+    } else {
+      _needsScrollViewBehaviorOverride = YES;
+    }
     [self updateContentScrollViewEdgeEffectsIfExists];
   }
 }